Good luck man. It takes a lifestyle change but you can easily lose about 2-3 pounds a week in a healthy way if you stay super active.
The best weight loss I've experienced was through my muay thai and mma classes. I probably lost about 5-6 pounds this summer (I'm slender as it is, but it was all bodyfat... I think I hover around 7% right now). Taking up an activity like that is a great way to lose weight, because you don't realize you're losing weight. It's just a by-product of the activity.
Make sure you drink a lot of water...
Also, before big pool parties or beach weekends, cut down on your sodium intake for a few days. Sodium makes you retain water. You will be ripped.